On 19 March 2013 09:04, Infinity <[email protected]> wrote: > Thanks for the pointer. I tried the following command, the error is better > in the sense that at least the DISPLAY variable is set this time > > sungrid-dev % qrsh -q galaxy_intr.q xclock > Error: Can't open display: localhost:16.0 > > localhost:16.0 is the DISPLAY variable on the sungrid-dev machine. I think > my main doubt is, what should be the DISPLAY variable on the final compute > cluster machine? This is what I don't really understand. > > The Xming server on my windows machine is running on localhost:0. So why is > the DISPLAY variable on the sungrid-dev machine localhost:16.0? Shouldn't it > be <windows_ip>:0? > Localhost doesn't just refer to your windows machine but to said machine's loopback interface which is only accessible from the machine itself. While X can be sent directly over the network it is a rather old protocol and the built in security/authentication mechanisms are rather suspect[1]. For this reason it is common to bind the X server to the loopback interface and forward over ssh as you appear to be doing. When you ask ssh to forward X the sshd on the machine you log in to creates a proxy X server (normally bound to its local interface) and forwards any traffic that server receives over the ssh connection back to the client which sends it to its local X server.
It looks like your qrsh command is forwarding the DISPLAY environment variable but since that points to sungrid_main's loopback interface it is not accessible from sungrid_dev. WARNING Bad Idea ahead: You might be able to work around this by using either netcat or an ssh from sungrid_main to itself (using port forwarding rather than X forwarding) to make the X server available on sungrid-main's cluster facing interface and setting DISPLAY manually. To pull this off you might need your initial ssh into the cluster to run its X-proxy in insecure mode (ie ssh -Y). This isn't Better Idea: Talk/e-mail to your cluster admins/local support. William [1] There are various security extensions for X that make its security better but support is spotty for most of them while ssh is available almost everywhere. _______________________________________________ users mailing list [email protected] https://gridengine.org/mailman/listinfo/users
